The Division Lycopodiophyta (sometimes called Lycophyta) is a tracheophyte subdivision of the Kingdom Plantae. It is the oldest extant (living) vascular plant division at around 420 million years old, and includes some of the most "primitive" extant species. These species reproduce by shedding spores and have macroscopic alternation of generations, although some are homosporous while others are heterosporous. They differ from all other vascular plants in having microphylls, leaves that have only a single vascular trace (vein) rather than the much more complex megaphylls found in ferns and seed plants.

Classification

There are around 1,200 living species divided into three main groups within the Lycopodiophyta, sometimes separated at the level of order and sometimes at the level of class. These are subdivided at the class level here:

• Class Lycopodiopsida – clubmosses and firmosses
• Class Isoetopsida – quillworts and scale trees
• Class Selaginellopsida – spikemosses. These are sometimes classified under Isoetopsida, with the order name "Selaginellales".